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Investments - Additional Information (Details) $ in Thousands		1 Months Ended	3 Months Ended	12 Months Ended
	Feb. 09, 2021	Mar. 31, 2020	Mar. 31, 2021 USD ($) security	Dec. 31, 2020 USD ($) security
Investment Holdings [Line Items]
Vertical risk retention interest	5.00%	5.00%	5.00%
Trading investments			$ 30,594	$ 16,923
Number of mortgage-backed securities with unrealized losses | security			40	14
Number of mortgage-backed securities | security			175	163
Available-for-sale investments, cost			$ 2,116,279	$ 1,986,957
Par value of mortgage-backed securities pledged to FRB			786,000	815,000
Non-marketable securities investment			26,000	26,000
Low income housing tax credit investments			52,000	54,000
Low income housing tax credit investments, liability for unfunded commitments			15,000	19,000
Low income housing tax credit investments, tax credits and benefits			$ 1,000	$ 6,000
Low income housing tax credit investments, expected tax benefits recognized			25.00%

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Affordable Housing Tax Credits and Other Tax Benefits, Percentage

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Amount of affordable housing tax credits and other tax benefits recognized.

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Amount of investment in qualified affordable housing projects.

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of commitment or contingent commitments to qualified affordable housing project investments.

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Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading).

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